Glaucoma is a leading cause of blindness in the world, and is commonly characterized by progressive optic neuropathy with associated visual field deficits. Estimates put the total number of suspected cases of glaucoma at over 70 million worldwide. Everyone is at risk for glaucoma, regardless of age: even though older people are at a higher risk for glaucoma, infants and children can suffer from glaucoma. High-risk groups include people over 60, family members of those already diagnosed, and people who are severely nearsighted.
Glaucoma usually results from fluid pressure building inside the eye until the optic nerve becomes damaged, leading to progressive, irreversible vision loss. The two main types of glaucoma are primary open-angle glaucoma and angle-closure glaucoma. Primary open-angle glaucoma causes 90% of glaucoma cases; its symptoms may include a loss of peripheral vision or tunnel vision. Symptoms of acute angle-closure glaucoma may include eye pain, blurred vision, nausea and/or vomiting, eye redness and seeing halos around lights. There are also low-tension or normal-tension forms, and congenital, pigmentary, and pseudoexfoliation forms of glaucoma. Secondary glaucoma can also develop as a complication from other medical conditions.
Although once sight is lost it cannot be recovered, it is possible, with treatment, to halt further vision loss caused by glaucoma. Glaucoma treatments include medicines, laser trabeculoplasty, conventional surgery, or a combination of any of these. Glaucoma medicines need to be taken regularly, and some medicines can cause headaches or other side effects. For example, drops may cause stinging, burning, and redness in the eyes. Because glaucoma often has no symptoms, people are often tempted to stop taking, or may forget to take, medicine. Compliance with eye drops regimens is especially problematic for the elderly. There remains a need for sustained release formulations for delivering glaucoma treatments.